Reviewing Data Acquisition Over Three Decades

A lot has changed since we designed converters from discrete components.

We’ve heard it many times before: “Analog is dead.” All digital means of treating a signal will emerge and make analog obsolete. Certainly digital chip fabrication has always been cheaper and easier to implement. Many more companies produce digital circuits than analog circuits. But as Mark Twain purportedly said, "The reports of my death are greatly exaggerated."

For analog measurement, the progress over these past three decades has been spectacular. Thirty years ago we matched transistors at night, about 400 pairs, just to get a decent amplifier front end. That changed to using pairs on the same substrate, then operational amplifiers matched for differential performance, and onward to 12-bit ADC and 12-bit DACs that were better than any converters made from discrete components. A loud vocal expert at the time said that a real 12-bit ADC IC could not be done, but we have long proven him wrong. Now we have standard, off-the-shelf 24-bit ADCs using oversampling and DSP methods to make incredibly high-performance devices. We also believe that we are just getting started.

It’s come a long way from a startup basement
Change for improvement is a continual path. Analog by itself is not able to achieve great application results. The aim today is introduce a product that gives high measurement performance, can be plugged into a system and used immediately, protects and isolates tiny pristine signals from noise and voltage spikes, and mates easily with the application software. But, the quest for great analog performance is not easy.

Data acquisition boards used to be built with ADCs and DACs made from discrete components.

I'm continually amazed at the multiple disciplines it takes to build our modules and systems for product introduction. Our weekly meeting pulls all the engineers together to discuss what has been done and what needs to be done. There are 15 people on a single product to report and discuss our progress: analog designer, digital designer, firmware developer, middleware developer, application software developer, documentation specialist, SQA engineer, diagnostics engineer, mechanical engineer, marketing specialist, manufacturing engineer, materials engineer, purchasing agents, management, and the folks from sales who want to make sure that the product is customer centric.

Government entities have made their way into our meetings as well. That's because quality of performance now involves CE and FCC design criteria for emissions and ESD testing to ensure quiet system operation. Design has been further complicated by the extensive use of switching power supplies to offer the various voltage levels needed to use evolving chip offerings. The positive side shows in keeping system power requirements down, especially for long battery life, but the higher frequency clocks introduce noise into analog ground paths.

The mating of analog and digital side by side has always been a struggle to preserve “noise-free” dynamic accuracy, but the addition of high frequency clocks and data are now landing in the analog realm, making the term “pure digital” just fiction. These issues manifest themselves throughout our everyday life, as well in mobile phones and WiFi.

We've come a long way from a startup basement. How has product development changed for you?